Life as an aspiring writer feels like a juggling and balancing act most of the time. Here are some of the things required to have a career as a screenwriter:

-Writing new material constantly.
-Rewriting already existing scripts.
-Begging friends, spouse and other writers for input on your stuff so you can do yet another rewrite.
-Submitting to agents, managers and producers.
-Going to events to meet new people so that you can submit to yet more people.
-Tracking submissions you made via email or phone.
-Printing, photocopying and mailing scripts to competitions, agents managers and producers. (I'm always happy to see a competitions that accepts PDF files, the same goes for producers, managers and agents)
-Watching movies and TV shows that are pertinent to what you are writing.

-Watching movies and TV shows because of your love for art. (That's why you're doing all this in the first place, isn't it?)
-Reading the blogs and trades so you get your entertainment news.
-Reading books about the craft of writing.
-Taking writing classes and going to seminars.
-Reading books that are pertinent to what you are writing.
-Reading books for the love of it and because reading will make you a better writer.
-Reading screenplays, produced, unproduced, for friends or for fun.

If think that's about it..
Oh, yeah, I almost forgot. A day job so you can pay for costs of being an aspiring writer. Make sure to squeeze that in somewhere.